In a conventional reverse blow-back type of dust collector, a large number of sleeve-type filter bags are suspended from a tube sheet by means of bag cups which are individually engaged in air sealed relation to the tube sheet. In the present day commercial types of blow-back dust collectors, each bag cup carries an air nozzle which also is air sealed relative to the bag cup and the tube sheet.
In some instances, such dust collectors may incorporate as many as 500 filter bags, each having a bag cup and air nozzle assembly, each of which assemblies must be individually air sealed to the main tube sheet structure. Normally the tube sheet structure is formed in sections, each of which may carry as many as 60 bag cups, although from 4 to 32 cups per tube sheet section is typical. The tube sheet sections are welded or bolted together to lie in a common plane within the dust collector.
One of the most time-consuming and expensive fabrication operations in the manufacture of dust collectors of this type arises in connection with the mounting of each of the bag cups and air nozzles in air sealed relation to the tube sheet. In the past, this operation has been performed by welding the bag cup and air nozzle in place or by gasketing the bag cup and air nozzle in place and riveting the parts to the tube sheet.
Another time-consuming operation is involved in applying the filter bag and cage to the bag cup, usually by means of a mechanical clamping band and fastener. Bag-to-bag clearances are small and the clamping operation is tedious and difficult.